1. Field of the Invention
The invention relates to devices for fabricating circuit boards and somewhat more particularly to devices for cooling freshly-soldered circuit boards after a mechanical soldering of heat-sensitive electrical components into such boards.
2. Prior Art
Mechanical soldering of heat-sensitive electrical components into circuit boards typically occurs at soldering temperatures in excess of 240.degree. C. Such relatively high temperatures jeopardize the electrical components, particularly where the allowable peak temperature is exceeded. Dynamic temperature measurements carried out on circuit boards undergoing fabrication have shown that the maximum temperature experienced by a circuit board occurs only after the actual soldering process for a component is completed. By cooling freshly-soldered components or circuit boards immediate after a soldering process, this dangerous temperature peak can be reduced in such a way that the components are unlikely to be jeopardized. Cooling of freshly-soldered components on circuit boards is generally carried out with compressed air which is blown through nozzles toward the soldered surface of the components and/or boards. These nozzles are arranged in one or more rows and directed obliquely toward freshly-soldered surfaces of the components/boards so that the freshly applied and essentially still liquid solder is not blasted away. The cooling effect, naturally, increases in proportion to the number of nozzles used and in proportion to the air speed (pressure) used.
The positioning of a plurality of nozzles involves structual difficulties, particularly when the cooling device is directly adjacent a solder bath or a soldering work station. The high air speed itself not only results in unsettled surrounding air but also increases the amount of wasted solder since the air flow extends over the surface of the closely adjacent soldering bath. Further, poor soldering results are achieved and compressed air systems are costly and potentially dangerous.